Designers of automotive vehicles have devised a veritable plethora of structures intended to control both dynamic deformation and energy absorption in the event of a frontal impact upon a vehicle. Such structures have, on occasion, used upper and lower frame rails. U.S. Pat. No. 6,695,393, which is assigned to the assignee of the present invention, discloses a vehicular front end structure having upper and lower frame rails connected by a fender apron. U.S. Pat. No. 4,919,474 shows a similar construction in which upper and lower members are connected by a fender apron. The structures of the '393 and '474 patents tie together the upper and lower frame rails before, during, and after an impact. Accordingly, both the upper and lower rails will serve to absorb energy from the beginning of an impact event. This means that the rate of energy absorption cannot be shaped as is possible with the present invention, because the present invention decouples the upper frame rail from the lower frame rail, at least at the onset of an impact event. As a result, the present system provides the ability to, in effect, shape the rate of energy absorption and hence, axial deformation of the front of the vehicle.